As is known, every vessel, regardless of its tonnage, that is moored astern to a wharf, requires at least three cables fixed to the land in order to keep it secured correctly: two cables that connect two points of the stern to the wharf and a cable that connects the stem to the sea bed.
The operations for mooring a vessel generally require the intervention of onboard personnel and ground personnel to perform the positioning and tensioning of the mooring cables. These operations, particularly in the presence of wind and waves, are often difficult and onerous and require perfect coordination between the helmsman, the onboard personnel and the ground personnel to conclude the operation in the shortest possible time.
If coordination among the assigned workers is not correct, damage to the vessel, to the wharf, to other vessels and to people is possible.
As is known, in fact, a vessel can be steered only if it is moving. When a vessel is not moving, the rudder is ineffective and the vessel remains in the grasp of the wind and waves. This situation always occurs in the mooring step and in the unmooring step at departure; in these cases, in order to keep the vessel stationary, the engine is not engaged. The direct consequence of this situation is that the vessel is unsteerable. In these conditions, timing is essential in gripping and fixing the mooring cables so as to block the vessel to prevent it from striking the pier and the nearby vessels or, vice versa, from moving away from the mooring place, forcing the helmsman to repeat the maneuver. During mooring operations, good coordination between the helmsman and at least one person of the crew is indispensable in order to secure the vessel with cables at the stern and at the stem, ensuring that a correct distance of the vessel from the pier and from the nearby vessels is maintained.
A similar situation occurs also during unmooring at departure.
The greater the displacement of the vessel, the greater the need becomes for the intervention of auxiliary personnel in order to avoid severe damage in these delicate steps.
In order to simplify and speed up the mooring operations, automatic mooring devices have been proposed which are generally composed of a coupling element which is connected to the vessel or to the mooring point, for example a pier or jetty or wharf, and a capture element which is connected to the mooring point or to the vessel and can be engaged by the coupling element.
These devices have the drawback of requiring significant interventions on the vessel and on the mooring point, which in addition to having substantial costs, modify significantly and permanently the line of the vessel and the appearance of the mooring point.